1 //===-- llvm/Support/MathExtras.h - Useful math functions -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains some functions that are useful for math stuff.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_SUPPORT_MATHEXTRAS_H
15 #define LLVM_SUPPORT_MATHEXTRAS_H
17 #include "llvm/Support/DataTypes.h"
21 // NOTE: The following support functions use the _32/_64 extensions instead of
22 // type overloading so that signed and unsigned integers can be used without
25 /// Hi_32 - This function returns the high 32 bits of a 64 bit value.
26 inline uint32_t Hi_32(uint64_t Value) {
27 return static_cast<uint32_t>(Value >> 32);
30 /// Lo_32 - This function returns the low 32 bits of a 64 bit value.
31 inline uint32_t Lo_32(uint64_t Value) {
32 return static_cast<uint32_t>(Value);
35 /// is?Type - these functions produce optimal testing for integer data types.
36 inline bool isInt8 (int64_t Value) {
37 return static_cast<int8_t>(Value) == Value;
39 inline bool isUInt8 (int64_t Value) {
40 return static_cast<uint8_t>(Value) == Value;
42 inline bool isInt16 (int64_t Value) {
43 return static_cast<int16_t>(Value) == Value;
45 inline bool isUInt16(int64_t Value) {
46 return static_cast<uint16_t>(Value) == Value;
48 inline bool isInt32 (int64_t Value) {
49 return static_cast<int32_t>(Value) == Value;
51 inline bool isUInt32(int64_t Value) {
52 return static_cast<uint32_t>(Value) == Value;
55 /// isMask_32 - This function returns true if the argument is a sequence of ones
56 /// starting at the least significant bit with the remainder zero (32 bit
57 /// version). Ex. isMask_32(0x0000FFFFU) == true.
58 inline bool isMask_32(uint32_t Value) {
59 return Value && ((Value + 1) & Value) == 0;
62 /// isMask_64 - This function returns true if the argument is a sequence of ones
63 /// starting at the least significant bit with the remainder zero (64 bit
65 inline bool isMask_64(uint64_t Value) {
66 return Value && ((Value + 1) & Value) == 0;
69 /// isShiftedMask_32 - This function returns true if the argument contains a
70 /// sequence of ones with the remainder zero (32 bit version.)
71 /// Ex. isShiftedMask_32(0x0000FF00U) == true.
72 inline bool isShiftedMask_32(uint32_t Value) {
73 return isMask_32((Value - 1) | Value);
76 /// isShiftedMask_64 - This function returns true if the argument contains a
77 /// sequence of ones with the remainder zero (64 bit version.)
78 inline bool isShiftedMask_64(uint64_t Value) {
79 return isMask_64((Value - 1) | Value);
82 /// isPowerOf2_32 - This function returns true if the argument is a power of
83 /// two > 0. Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
84 inline bool isPowerOf2_32(uint32_t Value) {
85 return Value && !(Value & (Value - 1));
88 /// isPowerOf2_64 - This function returns true if the argument is a power of two
89 /// > 0 (64 bit edition.)
90 inline bool isPowerOf2_64(uint64_t Value) {
91 return Value && !(Value & (Value - int64_t(1L)));
94 /// ByteSwap_16 - This function returns a byte-swapped representation of the
95 /// 16-bit argument, Value.
96 inline uint16_t ByteSwap_16(uint16_t Value) {
97 #if defined(_MSC_VER) && !defined(_DEBUG)
98 // The DLL version of the runtime lacks these functions (bug!?), but in a
99 // release build they're replaced with BSWAP instructions anyway.
100 return _byteswap_ushort(Value);
102 uint16_t Hi = Value << 8;
103 uint16_t Lo = Value >> 8;
108 /// ByteSwap_32 - This function returns a byte-swapped representation of the
109 /// 32-bit argument, Value.
110 inline uint32_t ByteSwap_32(uint32_t Value) {
111 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
112 return __builtin_bswap32(Value);
113 #elif defined(_MSC_VER) && !defined(_DEBUG)
114 return _byteswap_ulong(Value);
116 uint32_t Byte0 = Value & 0x000000FF;
117 uint32_t Byte1 = Value & 0x0000FF00;
118 uint32_t Byte2 = Value & 0x00FF0000;
119 uint32_t Byte3 = Value & 0xFF000000;
120 return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
124 /// ByteSwap_64 - This function returns a byte-swapped representation of the
125 /// 64-bit argument, Value.
126 inline uint64_t ByteSwap_64(uint64_t Value) {
127 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
128 return __builtin_bswap64(Value);
129 #elif defined(_MSC_VER) && !defined(_DEBUG)
130 return _byteswap_uint64(Value);
132 uint64_t Hi = ByteSwap_32(uint32_t(Value));
133 uint32_t Lo = ByteSwap_32(uint32_t(Value >> 32));
134 return (Hi << 32) | Lo;
138 /// CountLeadingZeros_32 - this function performs the platform optimal form of
139 /// counting the number of zeros from the most significant bit to the first one
140 /// bit. Ex. CountLeadingZeros_32(0x00F000FF) == 8.
141 /// Returns 32 if the word is zero.
142 inline unsigned CountLeadingZeros_32(uint32_t Value) {
143 unsigned Count; // result
145 // PowerPC is defined for __builtin_clz(0)
146 #if !defined(__ppc__) && !defined(__ppc64__)
147 if (!Value) return 32;
149 Count = __builtin_clz(Value);
151 if (!Value) return 32;
153 // bisecton method for count leading zeros
154 for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
155 uint32_t Tmp = Value >> Shift;
166 /// CountLeadingZeros_64 - This function performs the platform optimal form
167 /// of counting the number of zeros from the most significant bit to the first
168 /// one bit (64 bit edition.)
169 /// Returns 64 if the word is zero.
170 inline unsigned CountLeadingZeros_64(uint64_t Value) {
171 unsigned Count; // result
173 // PowerPC is defined for __builtin_clzll(0)
174 #if !defined(__ppc__) && !defined(__ppc64__)
175 if (!Value) return 64;
177 Count = __builtin_clzll(Value);
179 if (sizeof(long) == sizeof(int64_t)) {
180 if (!Value) return 64;
182 // bisecton method for count leading zeros
183 for (unsigned Shift = 64 >> 1; Shift; Shift >>= 1) {
184 uint64_t Tmp = Value >> Shift;
193 uint32_t Hi = Hi_32(Value);
195 // if some bits in hi portion
197 // leading zeros in hi portion plus all bits in lo portion
198 Count = CountLeadingZeros_32(Hi);
201 uint32_t Lo = Lo_32(Value);
202 // same as 32 bit value
203 Count = CountLeadingZeros_32(Lo)+32;
210 /// CountTrailingZeros_32 - this function performs the platform optimal form of
211 /// counting the number of zeros from the least significant bit to the first one
212 /// bit. Ex. CountTrailingZeros_32(0xFF00FF00) == 8.
213 /// Returns 32 if the word is zero.
214 inline unsigned CountTrailingZeros_32(uint32_t Value) {
216 return Value ? __builtin_ctz(Value) : 32;
218 static const unsigned Mod37BitPosition[] = {
219 32, 0, 1, 26, 2, 23, 27, 0, 3, 16, 24, 30, 28, 11, 0, 13,
220 4, 7, 17, 0, 25, 22, 31, 15, 29, 10, 12, 6, 0, 21, 14, 9,
223 return Mod37BitPosition[(-Value & Value) % 37];
227 /// CountTrailingZeros_64 - This function performs the platform optimal form
228 /// of counting the number of zeros from the least significant bit to the first
229 /// one bit (64 bit edition.)
230 /// Returns 64 if the word is zero.
231 inline unsigned CountTrailingZeros_64(uint64_t Value) {
233 return Value ? __builtin_ctzll(Value) : 64;
235 static const unsigned Mod67Position[] = {
236 64, 0, 1, 39, 2, 15, 40, 23, 3, 12, 16, 59, 41, 19, 24, 54,
237 4, 64, 13, 10, 17, 62, 60, 28, 42, 30, 20, 51, 25, 44, 55,
238 47, 5, 32, 65, 38, 14, 22, 11, 58, 18, 53, 63, 9, 61, 27,
239 29, 50, 43, 46, 31, 37, 21, 57, 52, 8, 26, 49, 45, 36, 56,
240 7, 48, 35, 6, 34, 33, 0
242 return Mod67Position[(-Value & Value) % 67];
246 /// CountPopulation_32 - this function counts the number of set bits in a value.
247 /// Ex. CountPopulation(0xF000F000) = 8
248 /// Returns 0 if the word is zero.
249 inline unsigned CountPopulation_32(uint32_t Value) {
251 return __builtin_popcount(Value);
253 uint32_t v = Value - ((Value >> 1) & 0x55555555);
254 v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
255 return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
259 /// CountPopulation_64 - this function counts the number of set bits in a value,
260 /// (64 bit edition.)
261 inline unsigned CountPopulation_64(uint64_t Value) {
263 return __builtin_popcountll(Value);
265 uint64_t v = Value - ((Value >> 1) & 0x5555555555555555ULL);
266 v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL);
267 v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL;
268 return unsigned((uint64_t)(v * 0x0101010101010101ULL) >> 56);
272 /// Log2_32 - This function returns the floor log base 2 of the specified value,
273 /// -1 if the value is zero. (32 bit edition.)
274 /// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1, Log2_32(6) == 2
275 inline unsigned Log2_32(uint32_t Value) {
276 return 31 - CountLeadingZeros_32(Value);
279 /// Log2_64 - This function returns the floor log base 2 of the specified value,
280 /// -1 if the value is zero. (64 bit edition.)
281 inline unsigned Log2_64(uint64_t Value) {
282 return 63 - CountLeadingZeros_64(Value);
285 /// Log2_32_Ceil - This function returns the ceil log base 2 of the specified
286 /// value, 32 if the value is zero. (32 bit edition).
287 /// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3
288 inline unsigned Log2_32_Ceil(uint32_t Value) {
289 return 32-CountLeadingZeros_32(Value-1);
292 /// Log2_64 - This function returns the ceil log base 2 of the specified value,
293 /// 64 if the value is zero. (64 bit edition.)
294 inline unsigned Log2_64_Ceil(uint64_t Value) {
295 return 64-CountLeadingZeros_64(Value-1);
298 /// GreatestCommonDivisor64 - Return the greatest common divisor of the two
299 /// values using Euclid's algorithm.
300 inline uint64_t GreatestCommonDivisor64(uint64_t A, uint64_t B) {
309 /// BitsToDouble - This function takes a 64-bit integer and returns the bit
310 /// equivalent double.
311 inline double BitsToDouble(uint64_t Bits) {
320 /// BitsToFloat - This function takes a 32-bit integer and returns the bit
321 /// equivalent float.
322 inline float BitsToFloat(uint32_t Bits) {
331 /// DoubleToBits - This function takes a double and returns the bit
332 /// equivalent 64-bit integer.
333 inline uint64_t DoubleToBits(double Double) {
342 /// FloatToBits - This function takes a float and returns the bit
343 /// equivalent 32-bit integer.
344 inline uint32_t FloatToBits(float Float) {
353 /// Platform-independent wrappers for the C99 isnan() function.
357 /// Platform-independent wrappers for the C99 isinf() function.
361 } // End llvm namespace